[PATCH v2] MIPS: Add support for CONFIG_DEBUG_VIRTUAL

* [PATCH v2] MIPS: Add support for CONFIG_DEBUG_VIRTUAL
@ 2021-03-23 22:20 Florian Fainelli
  2021-03-25  9:57 ` Thomas Bogendoerfer
  0 siblings, 1 reply; 4+ messages in thread
From: Florian Fainelli @ 2021-03-23 22:20 UTC (permalink / raw)
  To: linux-mips
  Cc: Florian Fainelli, Thomas Bogendoerfer, Randy Dunlap, Jiaxun Yang,
	Liangliang Huang, Huacai Chen, Geert Uytterhoeven,
	Anshuman Khandual, Kees Cook, Jinyang He, Vlastimil Babka,
	Yousong Zhou, Daniel Jordan, Michel Lespinasse, open list

Provide hooks to intercept bad usages of virt_to_phys() and
__pa_symbol() throughout the kernel. To make this possible, we need to
rename the current implement of virt_to_phys() into
__virt_to_phys_nodebug() and wrap it around depending on
CONFIG_DEBUG_VIRTUAL.

A similar thing is needed for __pa_symbol() which is now aliased to
__phys_addr_symbol() whose implementation is either the direct return of
RELOC_HIDE or goes through the debug version.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
Changes in v2:
- fixed sparse warning in arch/mips/kernel/vdso.c

 arch/mips/Kconfig            |  1 +
 arch/mips/include/asm/io.h   | 14 ++++++++-
 arch/mips/include/asm/page.h |  9 +++++-
 arch/mips/kernel/vdso.c      |  2 +-
 arch/mips/mm/Makefile        |  2 ++
 arch/mips/mm/physaddr.c      | 55 ++++++++++++++++++++++++++++++++++++
 6 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 arch/mips/mm/physaddr.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index d89efba3d8a4..0904d6351808 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,6 +4,7 @@ config MIPS
 	default y
 	select ARCH_32BIT_OFF_T if !64BIT
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
+	select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_PTE_SPECIAL if !(32BIT && CPU_HAS_RIXI)
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 78537aa23500..2c138450ad3b 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -100,11 +100,23 @@ static inline void set_io_port_base(unsigned long base)
  *     almost all conceivable cases a device driver should not be using
  *     this function
  */
-static inline unsigned long virt_to_phys(volatile const void *address)
+static inline unsigned long __virt_to_phys_nodebug(volatile const void *address)
 {
 	return __pa(address);
 }
 
+#ifdef CONFIG_DEBUG_VIRTUAL
+extern phys_addr_t __virt_to_phys(volatile const void *x);
+#else
+#define __virt_to_phys(x)	__virt_to_phys_nodebug(x)
+#endif
+
+#define virt_to_phys virt_to_phys
+static inline phys_addr_t virt_to_phys(const volatile void *x)
+{
+	return __virt_to_phys(x);
+}
+
 /*
  *     phys_to_virt    -       map physical address to virtual
  *     @address: address to remap
diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index 65acab9c41f9..195ff4e9771f 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -210,9 +210,16 @@ static inline unsigned long ___pa(unsigned long x)
  * also affect MIPS so we keep this one until GCC 3.x has been retired
  * before we can apply https://patchwork.linux-mips.org/patch/1541/
  */
+#define __pa_symbol_nodebug(x)	__pa(RELOC_HIDE((unsigned long)(x), 0))
+
+#ifdef CONFIG_DEBUG_VIRTUAL
+extern phys_addr_t __phys_addr_symbol(unsigned long x);
+#else
+#define __phys_addr_symbol(x)	__pa_symbol_nodebug(x)
+#endif
 
 #ifndef __pa_symbol
-#define __pa_symbol(x)	__pa(RELOC_HIDE((unsigned long)(x), 0))
+#define __pa_symbol(x)		__phys_addr_symbol((unsigned long)(x))
 #endif
 
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index 7d0b91ad2581..e3fd93ca480a 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -158,7 +158,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 
 	/* Map GIC user page. */
 	if (gic_size) {
-		gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT;
+		gic_pfn = virt_to_phys((void *)mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT;
 
 		ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
 					 pgprot_noncached(vma->vm_page_prot));
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index 865926a37775..fa1f729e0700 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -40,3 +40,5 @@ obj-$(CONFIG_R5000_CPU_SCACHE)	+= sc-r5k.o
 obj-$(CONFIG_RM7000_CPU_SCACHE) += sc-rm7k.o
 obj-$(CONFIG_MIPS_CPU_SCACHE)	+= sc-mips.o
 obj-$(CONFIG_SCACHE_DEBUGFS)	+= sc-debugfs.o
+
+obj-$(CONFIG_DEBUG_VIRTUAL)	+= physaddr.o
diff --git a/arch/mips/mm/physaddr.c b/arch/mips/mm/physaddr.c
new file mode 100644
index 000000000000..008b524a96b2
--- /dev/null
+++ b/arch/mips/mm/physaddr.c
@@ -0,0 +1,55 @@
+#include <linux/bug.h>
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/mmdebug.h>
+#include <linux/mm.h>
+
+#include <asm/sections.h>
+#include <asm/io.h>
+#include <asm/page.h>
+#include <asm/dma.h>
+
+static inline bool __debug_virt_addr_valid(unsigned long x)
+{
+	/* high_memory does not get immediately defined, and there
+	 * are early callers of __pa() against PAGE_OFFSET
+	 */
+	if (!high_memory && x >= PAGE_OFFSET)
+		return true;
+
+	if (high_memory && x >= PAGE_OFFSET && x < (unsigned long)high_memory)
+		return true;
+
+	/*
+	 * MAX_DMA_ADDRESS is a virtual address that may not correspond to an
+	 * actual physical address. Enough code relies on
+	 * virt_to_phys(MAX_DMA_ADDRESS) that we just need to work around it
+	 * and always return true.
+	 */
+	if (x == MAX_DMA_ADDRESS)
+		return true;
+
+	return false;
+}
+
+phys_addr_t __virt_to_phys(volatile const void *x)
+{
+	WARN(!__debug_virt_addr_valid((unsigned long)x),
+	     "virt_to_phys used for non-linear address: %pK (%pS)\n",
+	     x, x);
+
+	return __virt_to_phys_nodebug(x);
+}
+EXPORT_SYMBOL(__virt_to_phys);
+
+phys_addr_t __phys_addr_symbol(unsigned long x)
+{
+	/* This is bounds checking against the kernel image only.
+	 * __pa_symbol should only be used on kernel symbol addresses.
+	 */
+	VIRTUAL_BUG_ON(x < (unsigned long)_text ||
+		       x > (unsigned long)_end);
+
+	return __pa_symbol_nodebug(x);
+}
+EXPORT_SYMBOL(__phys_addr_symbol);
-- 
2.25.1


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